Webster's Revised Unabridged Dictionary · 1913

Deafen

Deafen , transitive verb

[From Deaf.]

1.
To make deaf; to deprive of the power of hearing; to render incapable of perceiving sounds distinctly.
Deafened and stunned with their promiscuous cries. — Addison
2.
(Architecture) To render impervious to sound, as a partition or floor, by filling the space within with mortar, by lining with paper, etc.